Spring集成MyBatis的三种实现方式

落日映苍穹つ 2023-07-13 03:06 19阅读 0赞

## 目录 ##

*  一、回顾MyBatis入门
 *  二、Spring集成MyBatis
 *  三、整合实现一
 *  四、整合实现二
 *  五、整合实现三

--------------------

# 一、回顾MyBatis入门 #

跳转到目录  
**也包括一些Spring需要的坐标**

<dependencies>
        
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.20</version>
            <scope>provided</scope>
        </dependency>
        
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.25</version>
            <scope>test</scope>
        </dependency>
        
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.40</version>
            <scope>runtime</scope>
        </dependency>
        
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.19</version>
        </dependency>
        
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.0</version>
        </dependency>
        
        
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.2.RELEASE</version>
        </dependency>
        
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.2.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.2.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.13</version>
        </dependency>
    </dependencies>

**数据库关系表设计**

CREATE TABLE `t_user` (
      `id` bigint(20) NOT NULL AUTO_INCREMENT,
      `name` varchar(20) DEFAULT NULL,
      `age` tinyint(4) DEFAULT NULL,
      `born_date` date DEFAULT NULL,
      `head_img` varchar(100) DEFAULT NULL,
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4;

**domain实体类**

@Data
    @AllArgsConstructor
    @NoArgsConstructor
    public class User { 
        private Long id;
        private String name;
        private Integer age;
        private Date bornDate;
        private String headImg;
    }

**实现mybatis的配置文件**

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
    
        <typeAliases>
            <package name="com.sunny.domain"/>
        </typeAliases>
    
        <environments default="development">
            <environment id="development">
                <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&useUnicode=true&characterEncoding=utf8"/>
                    <property name="username" value="root"/>
                    <property name="password" value="1111"/>
                </dataSource>
            </environment>
        </environments>
    
    	<mappers>
            <mapper resource="mappers/UserMapper.xml"/>
        </mappers>
    </configuration>
    </configuration>

**UserMapper接口编写**

public interface UserMapper { 
        List<User> selectAll();
    }

**接口对应的Mapper映射文件**

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    
    <mapper namespace="com.sunny.ssm.mapper.UserMapper">
    
        <resultMap id="BaseResultMap" type="User">
            <result property="id" column="id"/>
            <result property="name" column="name"/>
            <result property="age" column="age"/>
            <result property="bornDate" column="born_date"/>
            <result property="headImg" column="head_img"/>
        </resultMap>
    
        <select id="selectAll" resultMap="BaseResultMap">
            SELECT id, name, age, born_date, head_img FROM t_user;
        </select>
        
    </mapper>

**测试类**

public class UserMapperTest { 
        @Test
        public void test1() throws Exception{ 
            InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
            SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
            SqlSession sqlSession = factory.openSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            List<User> userList = mapper.selectAll();
            for (User user : userList) { 
                System.out.println(user);
            }
            sqlSession.close();
        }
    }

# 二、Spring集成MyBatis #

跳转到目录  
官方文档: [mybatis-spring][]

什么是 MyBatis-Spring？

*  MyBatis-Spring 会帮助你将 MyBatis 代码无缝地整合到 Spring 中。
 *  在开始使用 MyBatis-Spring 之前，你需要先熟悉 Spring 和 MyBatis 这两个框架和有关它们的术语。

MyBatis-Spring 需要以下版本：  
![在这里插入图片描述][20200309185119254.png]

Spring整合MyBatis, 主要目的就是把MyBatis核心配置文件中的内容,交给Spring来处理; 再简单点来说, 将MyBatis的`SqlSessionFactory`和`Mapper`的创建交给Spring处理;

### 1、简单介绍 ###

<dependencies>
        
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.0</version>
        </dependency>
    </dependencies>

![在这里插入图片描述][20200309185624733.png]

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzM3OTg5OTgw_size_16_color_FFFFFF_t_70]

<bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
            
            <constructor-arg index="0" ref="sqlSessionFactory"/>
        </bean>

现在，这个 bean 就可以直接注入到你的 DAO bean 中了。你需要在你的 bean 中添加一个 SqlSession 属性，就像下面这样：

public class UserMapperImpl implements UserMapper{ 
        
        private SqlSessionTemplate sqlSession;
    
        public void setSqlSession(SqlSessionTemplate sqlSession) { 
            this.sqlSession = sqlSession;
        }
    
        public List<User> selectAll() { 
            return sqlSession.getMapper(UserMapper.class).selectAll();
        }
    }

按下面这样，注入 `SqlSessionTemplate`：

<bean id="userMapperImpl" class="com.sunny.ssm.mapper.UserMapperImpl">
            <property name="sqlSession" ref="sqlSession"/>
        </bean>

# 三、整合实现一 #

跳转到目录

#### 1、创建Spring配置文件applicationContext.xml ####

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

#### 2、配置数据源替换mybaits的数据源 ####

db.properties

#连接数据库的四个基本要素
    jdbc.driverClassName=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://localhost:3306/ssm
    jdbc.username=root
    jdbc.password=1111
    #druid连接池其他配置,省略

<context:property-placeholder location="classpath:db.properties" system-properties-mode="NEVER"/>
    
    <bean id="myDataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
        <property name="driverClassName" value="${jdbc.driverClassName}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>

#### 3、配置SqlSessionFactory，关联MyBatis ####

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        
        <property name="dataSource" ref="myDataSource"/>
        
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        
        <property name="typeAliasesPackage" value="com.sunny.ssm"/>
        
        <property name="mapperLocations" value="classpath:mappers/*Mapper.xml"/>
    </bean>

#### 4、注册sqlSessionTemplate，关联sqlSessionFactory； ####

<bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
        
        <constructor-arg index="0" ref="sqlSessionFactory"/>
    </bean>

#### 5、增加Mapper(Dao)接口的实现类；私有化sqlSessionTemplate ####

#### 6、注册bean实现 ####

#### 7、测试 ####

@Test
    public void test1() throws Exception{ 
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserMapper userMapper = context.getBean("userMapperImpl", UserMapper.class);
        for (User user : userMapper.selectAll()) { 
            System.out.println(user);
        }
    }

结果成功输出！现在我们的Mybatis配置文件的状态！发现都可以被Spring整合！

其实我们可以通过Spirng完全将mybatis配置文件去除,这里还是保留一个配置吧!

# 四、整合实现二 #

跳转到目录  
让Dao继承Support类 , 直接利用 `getSqlSession()`获得 , 然后直接注入`SqlSessionFactory` . 比起方式1 , 不需要管理SqlSessionTemplate , 而且对事务的支持更加友好

官方文档截图:  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzM3OTg5OTgw_size_16_color_FFFFFF_t_70 1]

#### 1、将我们上面写的UserMapperImpl修改一下 ####

public class UserMapperImpl extends SqlSessionDaoSupport implements UserMapper { 
        public List<User> selectAll() { 
            return getSqlSession().getMapper(UserMapper.class).selectAll();
        }
    }

#### 2、修改bean的配置 ####

#### 3、测试 ####

@Test
    public void test2() throws Exception{ 
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserMapper userMapper = context.getBean("userMapperImpl", UserMapper.class);
        for (User user : userMapper2.selectAll()) { 
            System.out.println(user);
        }
    }

# 五、整合实现三 #

跳转到目录  
前两种的整合实现方式,都创建了Dao接口的实现类,通过实现类来获取mapper对象;  
使用整合方式三,我们告诉Spring,让他来帮我们创建mapper的代理对象即可!

#### 1、**配置MapperFactoryBean,Spring帮我们创建 Mapper的代理对象** ####

<bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
        <property name="sqlSessionFactory" ref="mySqlSessionFactory"/>
        
        <property name="mapperInterface" value="com.sunny.ssm.mapper.UserMapper"/>
    </bean>
    
    或者采用下面扫描的方式
    
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    	<property name="basePackage" value="com.sunny.mapper"/>
    </bean>

此时的applicationContext.xml文件; 其他和方式一相同  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzM3OTg5OTgw_size_16_color_FFFFFF_t_70 2]

#### 2、测试 ####

public class UserMapperTest { 
        @Autowired
        private UserMapper userMapper;
    
        @Test
        public void testSelectAll(){ 
            /* // 非DI注入的方式 ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); UserMapper mapper = context.getBean("userMapper", UserMapper.class); for (User user : mapper.selectAll()) { System.out.println(user); }*/
    
            // DI注入方式
            List<User> users = userMapper.selectAll();
            for (User user : users) { 
                System.out.println(user);
            }
        }
    }

**此时, 通过DI注入的方式获取到mapper对象,然后进行CRUD即可!**

#### 总结 : 整合到spring中以后可以完全不要mybatis的配置文件，除了这些方式可以实现整合之外，我们还可以使用注解来实现 ####

[mybatis-spring]: http://mybatis.org/spring/zh/getting-started.html
[20200309185119254.png]: https://img-blog.csdnimg.cn/20200309185119254.png
[20200309185624733.png]: https://img-blog.csdnimg.cn/20200309185624733.png
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